The ArmCom EMR Shocker was a premade Heavy Assault Rifle that used electro ammo. This HAR sacrifices a little bit of damage for a little bit of accuracy to better electrocute your foes. Also this weapon is non-customizable and attachments on this weapon cannot be used on other weapons.
Post Parity Patch
After the Parity Patch was released premades could no longer be purchased. See Premades for more information.